Brick-drying floor.



PATBNTED'OGT. zo, 1903. 4

l H.' W. cRoPT. BRIGKDRYINGFLOUR. vANLIOA'IJION FILED AUG. 8.. 1902.

NO MODEL.

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ivo. 7471,6o.

- UNITED kSTATES atented October I20, 1905;.

PATENT OFFICE.

BR'lCK-DRYIN'G FLOOR.-

SPECIFICATION forming part of Letters Patent No. 741,6eo, dated october' ao, ieo.

Application led Augnst', 1902. Serial No, 118,878. (No model.)

To @ZZ whom it may concern:

Beitknown that I, HARRY W'. CROFT, a resi.

ble to use a smaller Vproportion of bonding ma-v terial in conjunction with the refractory material.

My apparatus is of especial value in the manufacture of fire-brick.; but it is equally as well adapted for the manufacture of brick of any kind or description.

In the manufacture of fire-brick it is customary to grind the material, add water, and temper the mass by various methods, and then it is molded into the desired shape, after which the molded brick are partially dried, then pressed, and finally are thoroughly dried preparatory to burning. The 'rst drying is accomplished by laying the brick singlyon a hot Hoor heated by fire-fines or steam-pipes laid therein. The floor is heated as highly as possible, the temperature varying from 150 to 200 Fahrenheit, so that the preliminary drying of the brick is accomplished in from two to Vfive hours. The iioor only is heated, so that the temperature at the floor is materially higher than the air in the chamber just above the same. This preliminary drying removes only a part of the moisture in the brick, the latter being left in such condition that they Will not crumble or break in pressing. After being pressed the brick are again dried by being either piled from three to six high on a part of the hot floor, above described, and dried by the heat from the latter, or they are laid'singly on pallets placed on cars and run into tunnels and there dried either byfhot steampipes running underneath the cars orv by a hot blast of air forced in at one part of the tunnel and taken out at another. The temperature during'this sec,- ond drying step is also practically as high as can be obtained, and it is customary to subject the brick to this temperature about twenty-four hours, so as to thoroughly dryl out the same preparatory to burning.

The principal objection to the above method is that the brick are dried too rapidly, so that the exposed surfaces thereof, and especially the corners, become fixed or rigid, while the interior and bottom are still wet, -As a con-v sequence the surfaces and corners shrink more rapidly than the interior, thus producing cracks in the corners and surfaces of the brick,l and when the moisture afterward leaves the interior the latter shrinks away from the rigid exterior crust, thus forming innumerable small cracks all through the body of the brick. The surface cracks usually extend into the brick for about one-half inch and can be readily detected. The cracks formed in the preliminary drying are to some extent obliterated in the pressing, sothat they may no longer be visible, but the mate- `rial being drier .in the cracks than elsewhere v,does not firmly unite or knit, so that the cracks reappear after the second drying or burning. They destroy the* adhesiveness of the mass, so that after the brick are burned instead of having a clear metallic ring they will have a dull-lifeless sound, similar to that of cracked earthenware,v As a consequence of these cracks a very large number of broken bricks orl bats are 'usually produced, and

even those that do not break when used as f refractory linings for furnaces instead of wearing away'uniformly chip or break away, and the life thereof 4is very'much shorter than that of a brick free from cracks. In order toevercome this defect, it has been customary to use quite a large percentage of adhesive clay with the refractory material, thus increasing the bonding strength of the` brick. This, however, results in reducing the refractory character of the brick. The object of my invention is to provide apparatus which will so dry the brick that the cracking thereof at the surface and corners and throughout the body thereof is entirely or largely avoided, thus making it posroo Y sible to use a smaller percentage of adhesive material and correspondingly increasing the refractory character of the brick and producing a brick which in use will wear awa gradually and not chip or crack off.

In the accompanying drawings, Figure 1 is a longitudinal section through my improved apparatus. Fig. 2 is an end view of the heating apparatus, the same being partly in section. Fig. 3 is a transverse'view on theline 3 3, Fig. 1. Fig. 4 is a section through a brick after the preliminary drying according to the old method, and Fig. 5 is a section of brick after the second drying according to the old method. y l

My apparatus is constructed so as to dry the brick by subjecting them to a moderate heat and uniformlyon all faces thereof. Any suitable apparatus for accomplishing this result may be employed. In the drawings I have shown a heating-chamber l, provided with a floor 2, of porous material, preferably furnace-slag concrete. This loor is heated to a moderate temperature by any desired means-such, for instance, as hot-air fines 3 laid therein. These tlues may be of any desired construction, but preferably are ordinary terra-colta drain-tiles from three to four inches in diameter and laid in the furnaceslag concrete. The latteris first ground and mixed with water and then filled in underneath, around, and above the ilues, and the top thereof presents a smooth firm surface which cannot be readily disturbed or disiigured. It is, however, quite porous, so that the moisture of the brick will be absorbed thereby. These dues may receive their heat from any suitable source, and I have shown one end thereof connected to a header 5,which latter is connected, by means ofa flue 6,to a larger flue 7, the latter being connected to an air-heating chamber 8. The air in the chamber 8 may be heated to a moderate temperature by any desirable or convenient means, and I have shown for this purpose a coil 9, which h as connected thereto a pipe 10, leading from the exhaust of a steam-engine or the like. The air is drawn through the chamber 8 by means of a fan 1l at such a rate that it will be maintained at a moderate temperature somewhat above 75o to 100 Fahrenheit and is forced by the fan into the flue 7 and from there passes, by means of the flue 6, to the header 5 and through the flues 3, embedded in the loorof the heating-chamber. The farther ends of the flues 3 communicate with the chamber l by means of the short sections ofpipel2. Theiue'isprojectedintotheheating-cham ber 1, as shown, and at intervals has connected thereto depending pipes 14, which project downwardly and have theirlower ends bent and directed somewhat upwardly, as at l5, so that the hot air colning therefrom will not be projected against the brick lying on the floor of the chamber. The flue 7decreases in size, as shown, and its outer end is open,

as at 16. The decrease in size of the Ilue '7 will insure the heat being about equally distributed through the various pipes 14 and the outlet 16, so that all portions of the chamber will receive approximately the same amount of heat.

It is essential with my invention to maintain a moderate and uniform temperature in the heating-chamber and floor, and this can be attained best by connecting to the airflues some form of hot-air heating apparatus, as distinguished from fire-fines. With the latter the flame and waste products ot' combustion necessarily pass through the flues, so

steam, or other medium used for heating theA air.

In Figs. 4 and 5 are shown sections of brick illustrating the defects occurring with the old drying apparatus. When the brick tirst come from the molds, they are necessarily very wet, and when laid on the hot floor of the old apparatus the intense heat rising from the lloor quickly draws the moisture from the exposed surfaces, and particularly from the corners, of the brick, while the moisture from the lower portion of the brick, being unable to escape as rapidly as drawn out by the intense heat employed, collects underneath the brick, so that the lower part of the brick remains in a wet or moist condition, as indicated by the heavy shading at 18, Fig. 4, while the exposed surfaces, and especially the corners, of the brick will be full of minute cracks, as shown, there being a tendency especially to form about three large cracks on the upper surface, which extend down into the brick a considerable distance. This preliminary drying, as above stated, is not continued sufciently long to thoroughly dry the brick, as the latter must be left suficiently plastic to stand the pressing operation. During the pressing operation the wet or soggy portion at the bottom of the brick to some extent disappears, as the moisture scatters or becomes dispersed throughout the body of the brick. The pressure exerted on the brick during the pressing closes up the cracks in the brick, so that they are not so easily visible; but as the clay is somewhat drier in the cracks than elsewhere it is too dry to unite or knittogether even under very great pressure, so that these cracks open up again more or less either in the drying-tunnel or when stacked on the floor three to six high IOO IIO

collection of the latter underneath the brickv does not occur. As a consequence the under surface is dried very quickly and baked into a hard crust before the middle and upper portions are dried. The violent heat rising from the floor draws the moisture from the corners and exposed surfaces so rapidly that these also become baked, while the center of the brick still remains damp or moist, as

` shown by the heavy shading 19 in Fig. 5.

When the interior afterward dries, it shrinks away fr om the fixed exterior-crust, andthis causes numerous small cracks .to be formed throughout the body of the brick. The cracks are usually much more marked on the surface next to the floor and also much-'more marked in the tiers or layers nearest the floor, this being due to the fact that the temperature in the chamber decreases appreciably as the distance from the iioor`increases. Most of the broken bricks or bats come from the two layers nearest the floor.

In the use of my improved apparatus the wet brick after being molded are placed singly upon the door of the chamber. Both the ioor of the chamber and the air in the chamber itself are heated to approximately the same moderate temperature, from about 75 to 100 Fahrenheit, so that all surfaces of the brick are exposed to this uniform moderate temperature, and the moisture in the wet brick is absorbed or drawn out of the brick uniformly on all faces thereof and at such a slow rate that the moisture inthe interior of the brick will have au opportunity to pass out before the exterior of the brick has become hard or baked. The blast-furnace slag comprising the ioor is sufficiently porous to absorb the moisture from the lower face of the brick in a gradual and uniform manner and at about the same rate that it is being drawn from the brick, so that the wet or soggy under surface of the old method is avoided. As a consequence the shrinkage of the brick is uniform throughout and the cracks resulting in the old apparatus are absent. The preliminary drying at this moderate temperature 'is continued for about twenty-four hours, as compared to from two to five hours with the old apparatus. After the brick have been tempered as described at the uniform low temperature they are pressed in any suitable press and piled from three to six or eight high on the ioor and allowed to remain until thoroughly dry, the drying again taking place slowly under the moderate 'and parts of 4the chamber.

uniform temperature described and avoiding the oldV processes and requiring three days instead of one day, as under the old methods. Theresult, however, is a brick which is free from cracks and which, therefore, is m'uch stronger and has much greater wearing qualities than the old brick. Furthermore, it is possible to use a much smaller proportion of plastic or bonding clay in proportion to the refractory clays or Hints. It has been proved by actual test that under my process brick containing ten per cent. of plastic or bonding clay are equal in strength, bond, 'and resistance to abrasion tobrick made under the old method and containing twenty-five per cent. of plastic or bonding clay. The brick under my method, therefore, can be made of a much greater refractory character, and the number of broken bricksv or bats, which are a dead loss, is very largely reduced. The moderate temperature employed does not evaporate the moisture from the surfaces of the brick any more rapidly than it can be supplied by capillary attraction from the interior thereof. As a consequence the brick will dry uniformly throughout. Furthermore, the moderate temperature enables a more uniform heat to be maintained in all These drying-chambers necessarily are very long, and a high temperature introduced in the lues underneath the floor will drop materially before it has traversed the entire length thereof, so that there will be very appreciable dier ences in temperature at the two 'ends of the floor. With a moderate temperature employed such marked differences do not exist..

The use of hot air in the heating-nues is also advantageous, especially when used in .terra-y cotta dues, such as shown. a very strong ainity for the moisture, being a dry heat, as distinguished from the wet heat of steam, and it will therefore draw the mois-v ture from the under side of the brick through the porous floor and flues instead of causing the moisture to form a puddle and simmer, as is the case with a very hot non-porous door or one heated by a moist heat, such as steam. l

While my invention has been described particularly for use inl the manufacture of fire-brick, it will be understood that it is equally aswell adapted for the manufacture of ordinary clay building-brick or, in fact, for brick, blocks, or tiles of` any kind or description.

What I claim is` V l. Brick -drying apparatus Vcomprising a chamber provided with a porous'iloor, porous heating-fines laid therein, a flue leading into heating apparatus connected to said fines.

2. Brickdrying Vapparatus comprising a The hot air has 'IOO 'the chamber above the' iioo'r, and hot-fair` chamber having a floor of porous material, ber Connected to said iiues, and a steam-coi1 Io heating-iiues'laid therein, a heatiug-ue prolocated in said air-heating chamber. jectng into the chamber above theiloor, and In testimony whereof I, the said HARRY W. hot-air heating apparatus connected to said CROFT, have hereunto set my hand. 5 Iiues. A T 1 3., Brickdrying apparatus comprising a HARRX W OROFrl' heatingchamber, heating-fines laid in the Vitnesses: Hoor thereof,aheatingf1ue projecting into the A. M. STEEN, chamber above the Hoor, an air-heating cham- ROBT. 2D. TOTTEN. 

